The present invention relates to a method of producing a pattern-formed structure, which structure is less likely to deteriorate as time elapses after the characteristic thereof is modified by using a photocatalyst, because no photocatalyst exists in the resulting pattern-formed structure. The present invention also relates to a photomask which can be used in the aforementioned method of producing a pattern-formed structure.
As the conventional method of forming a highly elaborate pattern, is generally known a method of producing a pattern-formed structure by photolithography, such as a method which includes the processes of; carrying out pattern-exposure of a photoresist layer provided by coating on a base material; developing the photoresist after the exposure; and effecting etching of the developed photoresist layer, and a method which includes the processes of: employing a functional substance as the photoresist; and directly forming the aimed pattern by exposure of the photoresist.
The methods of forming a highly elaborate pattern by lithography have already been employed in formation of a colored pattern of a color filter used in a liquid crystal display or the like, formation of a microlens, production of an elaborate electric circuit board, production of a chrome mask used for pattern exposure, and the like. However, in such methods, it is necessary to use a photoresist, effect development with a liquid developer after exposure and (depending on the method) carrying out etching. Therefore, a problem arises, e.g., in that the waste liquid must be properly treated before discarding. In a case in which a functional substance is used as the photoresist, another problem arisess in that the product deteriorates due to the alkali solution used in the development process.
Formation of a highly elaborate pattern such as a color filter by printing has also been attempted. However, a pattern formed by printing tends to cause a problem in the precision of positioning, whereby highly precise pattern formation is difficult by this method.
On the other hand, in order to solve such problems as described above, the inventors of the present invention and other researchers have studied a method of producing a pattern-formed structure in which method a pattern is formed by using a substance whose wetting property is modified by the action of a photocatalyst. However, in such a conventional method of producing a pattern-formed structure by the action of a photocatalyst, the produced pattern-formed structure itself structurally includes the photocatalyst therein, whereby, depending the type of the pattern-formed structure, a problem arises in that the product may deteriorate due to the photocatalyst contained therein.
The present invention is provided in order to solve the above-described problems. The main object of the present invention is to provide a method of producing a pattern-formed structure, in which method a highly precise pattern formation is possible in production of a pattern-formed structure, no post-exposure treatment is required and no photocatalyst is contained inside the produced pattern-formed structure, whereby there is no concern that the obtained pattern-formed structure deteriorates.
In order to achieve the above-described object, a method of producing a pattern-formed structure, comprises the processes of: preparing a substrate for a pattern-formed structure having a characteristic-modifiable layer whose characteristic at a surface thereof can be modified by the action of photocatalyst; arranging the substrate for a pattern-formed structure and a photocatalyst-containing-layer side substrate having a photocatalyst-containing layer formed on a base material, the photocatalyst-containing layer containing photocatalyst, such that the characteristic-modifiable layer faces the photocatalyst-containing layer with a gap of no larger than 200 xcexcm therebetween; and irradiating energy to the characteristic-modifiable layer from a predetermined direction, and modifying characteristic of a surface of the characteristic-modifiable layer, thereby forming a pattern at the characteristic-modifiable layer.
According to the present invention, a pattern having various properties can be formed in a highly precise manner, without necessity of any specific treatment after irradiation of energy. Further, as the photocatalyst-containing-layer side substrate is removed form the pattern-formed structure after irradiation of energy, the pattern-formed structure itself includes no photocatalyst-containing layer, whereby there is no possibility that the pattern-formed structure deteriorates as time elapses by the action of the photocatalyst. Yet further, in the present invention, as the gap or space between the photocatalyst-containing layer and the characteristic-modifiable layer is set within the above-described range, a pattern-formed structure having a pattern produced as a result of modification of characteristic thereof can be obtained in an efficient and highly precise manner.
In the present invention, the photocatalyst-containing layer and the characteristic-modifiable layer are preferably disposed such that the gap therebetween is in a range of 0.2 to 10 xcexcm. As the gap between the photocatalyst-containing layer and the characteristic-modifiable layer is set in a range of 0.2 to 10 xcexcm, a pattern-formed structure having a pattern produced as a result of modification of characteristic thereof can be obtained by irradiation of energy in a relatively short time.
In the present, the photocatalyst-containing-layer side substrate is preferably constituted of the base material and a photocatalyst-containing layer formed, in a pattern-like configuration, on the base material. By forming the photocatalyst-containing layer in a pattern-like configuration as described above, a pattern having a different characteristic can be formed on the characteristic-modifiable layer, without using a photomask. Further, as only the characteristic of the portion, of the characteristic-modifiable layer surface, corresponding to the photocatalytic-containing layer is modified, the type of energy to be irradiated is not particularly restricted to energy provided in parallel and the direction of irradiating energy is not particularly restricted, either. Accordingly, in this appect, the degree of freedom in the types of the energy source and the arrangement thereof is significantly increased, which advantageous.
In the present, it is preferable that the photocatalyst-containing-layer side substrate is constituted of the base material, the photocatalyst-containing layer formed on the base material, and a light-shielding portion formed in a pattern-like configuration, and the irradiation of energy at the aforementioned pattern forming process is carried out from the photocatalyst-containing-layer side substrate.
Providing the light-shielding portion in the photocatalyst-containing-layer side substrate as described above renders use of a photomask or the like during energy irradiation obsolete. Accordingly, the process of aligning the photocatalyst-containing-layer side substrate with a photomask, or the like, is no longer required, contributing to simplifying the whole production processes.
In the present, in the photocatalyst-containing-layer side substrate, the light-shielding portion is formed, in a pattern-configuration, on the base material and the photocatalyst-containing layer is formed on the light-shielding portion.
Alternatively, in the present, in the photocatalyst-containing-layer side substrate, the photocatalyst-containing layer is formed on the base material and the light-shielding portion is formed, in a pattern-configuration, on the photocatalyst-containing layer.
It is preferable that the light-shielding portion is disposed at a position close to the characteristic-modifiable layer, in terms of enhancing precision of the resulting characteristic pattern. Therefore, it is preferable that the light-shielding portion is disposed at the above-described position. Further, in a case in which the light-shielding portion is provided on the photocatalyst-containing layer, the light-shielding portion can serve as a spacer when the photocatalyst-containing layer is disposed with respect to the characteristic-modifiable layer in the aforementioned pattern forming process, which is advantageous.
In the present, in the photocatalyst-containing-layer side substrate, a spacer having thickness in a range of 0.2 to 10 xcexcm is formed in a pattern-like configuration, on the photocatalyst-containing layer and exposure is effected in a state in which the spacer is in contact with the characteristic-modifiable layer.
In the present, a spacer is provided in a pattern-like configuration on the photocatalyst-containing layer and exposure is effected in a state in which the spacer is in contact with the characteristic-modifiable layer. As a result, the distance between the photocatalyst-containing layer and the characteristic-modifiable layer can be easily kept in a range of 0.2 to 10 xcexcm. Further, as the portions of the photocatalyst-containing layer on which the spacer has been formed is covered by the spacer, these portions do not cause any modification to the corresponding portions of the characteristic-modifiable layer upon irradiation of energy. Accordingly, the same pattern as that of the spacer can be formed on the characteristic-modifiable layer as a result of the characteristic modification thereof.
In the present, the spacer is preferably a light-shielding portion made of a light-shielding material. As the spacer serves as a light-shielding portion, a highly precise pattern can be formed by effecting irradiation of energy in a state in which the light-shielding portion is in close contact with the characteristic-modifiable layer.
The present invention also provides a method of producing a pattern-formed structure, comprising the processes of: preparing a photocatalyst-containing-layer side substrate in which a photocatalyst-containing layer is formed on a photomask by way of a primer layer, the photomask being formed by providing a light-shielding portion, in a pattern-like configuration, on a transparent base material; preparing a substrate for a pattern-formed structure having a characteristic-modifiable layer whose characteristic can be modified by the action of photocatalyst contained at least in the photocatalyst-containing layer; arranging the photocatalyst-containing-layer side substrate and the substrate for a pattern-formed structure: such that the photocatalyst-containing layer and the substrate for a pattern-formed structure are in contact with each other; or such that the characteristic-modifiable layer faces the photocatalyst-containing layer with a gap therebetween, the gap being narrow enough to allow the action of the photocatalyst of the photocatalyst-containing layer to effect on the characteristic-modifiable layer; effecting irradiation of energy to the substrates, thereby modifying characteristic of the irradiated portion of the characteristic-modifiable layer; and removing the photocatalyst-containing-layer side substrate, thereby obtaining a pattern-formed structure.
According to the present, a pattern can be produced with high sensitivity and in a highly precise manner, without necessity of carrying out any specific treatment after irradiation of energy. Further, as the photocatalyst-containing-layer side substrate is removed from the pattern after the irradiation of energy, the characteristic-modifiable-layer side substrate itself does not include any photocatalyst-containing layer. Therefore, there arises no concern that the characteristic-modifiable-layer side substrate deteriorates as time elapses by the action of the photocatalyst. Further, the residuals or the like generated at the light-shielding portion at the time of patterning and existing thereafter at the light-shielding portion or the opening portion between one light-shielding portion and the other do not affect the action of the photocatalyst, as a result of the excellent effect of the primer layer. Accordingly, the sensitivity of the photocatalyst can be enhanced and a pattern, produced as a result of modification of characteristic, can be obtained even by irradiation of energy in a relatively short time.
In the present invention, it is preferable that the gap which is narrow enough to allow the action of the photocatalyst of the photocatalyst-containing layer to effect on the characteristic-modifiable layer is in a range of 0.2 to 10 xcexcm. As the gap between the photocatalyst-containing layer and the characteristic-modifiable layer is in a range of 0.2 to 10 xcexcm, a pattern-formed body having a pattern produced as a result of modification of characteristic thereof can be obtained by irradiation of energy in a relatively short time.
In the present, it is preferable that the photocatalyst-containing layer is a layer made of photocatalyst. When the photocatalyst-containing layer is made of only photocatalyst, the efficiency at which the characteristic of the characteristic-modifiable layer is modified can be enhanced, whereby a pattern-formed structure can be efficiently produced.
In the present, it is preferable that the photocatalyst-containing layer is a layer formed by providing a photocatalyst in a form of a film or a base material by a vacuum film making method. By forming the photocatalyst-containing layer according to the vacuum film making method, a photocatalyst-containing layer having constant film thickness and less irregularities at the surface thereof can be produced, whereby formation of the characteristic pattern at the characteristic-modifiable layer surface can be performed evenly and in a higly efficient manner.
In the present, it is acceptable that the photocatalyst-containing layer is a layer containing a photocatalyst and a binder. By using a binder in such a manner, the photocatalyst-containing layer can be formed relatively easily, whereby a pattern-formed structure can be produced at a low cost.
In the present, it is preferable that the photocatalyst is at least one type of compound selected from the group consisting of titanium oxide (TiO2) zinc oxide (ZnO), tin oxide (SnO2), strontium titanate (SrTiO3), tungsten oxide (WO3), bismuth oxide (Bi2O3) and iron oxide (Fe2O3)
In the present, it is preferable that the photocatalyst is titanium oxide (TiO2). Titanium dioxide, having high band gap energy, acts effectively as a photocatalyst, is chemically stable, has no toxicity, and is easily available.
In the present invention, it is preferable that the substrate for a pattern-formed structure is constituted, at least, of a substrate and the characteristic-modifiable layer provided on said substrate. As a characteristic-modifiable layer generally has various characteristics, it is preferable that the characteristic-modifiable layer is formed as a thin film on the substrate, in terms of strength, cost efficiency and functional aspects.
In the present invention, it is preferable that the characteristic-modifiable layer is a wetting-property-modifiable layer whose wetting property can be modified, such that a contact angle formed by a liquid on said wetting-property-modifiable layer is decreased upon irradiation of energy by the action of the photocatalyst in the photocatalyst-containing layer. Examples of the characteristic of the characteristic-modifiable layer include various characteristics, and one important example thereof is the change in the wetting property. By designing the characteristic-modifiable layer as a wetting-property-modifiable layer, a pattern-formed structure having a pattern produced as a result of modification of the wetting-property thereof by the action of the photocatalyst can be obtained. Accordingly, by attaching a composition for the functional portion such as ink to the site where the wetting property has been modified, various types of functional elements, including a color filter and a microlens, can be formed as described below.
In the present invention, it is preferable that the contact angle formed on said wetting-property-modifiable layer by a liquid whose surface tension is 40 mN/m is no smaller than 10xc2x0 at an unexposed portion of the layer and no larger than 9xc2x0 at an exposed portion. The portion which is not subjected to energy irradiation is a portion which is required to exhibit liquid-repellency and the portion which is subjected to energy irradiation is a portion which is required to exhibit lyophilicity. Therefore, the wetting property as described above is necessary in the wetting-property-modifiable layer.
In the present invention, it is preferable that said wetting-property-modifiable layer is a layer containing organopolysiloxane.
In the present invention, it is preferable that the organopolysiloxane is a polysiloxane containing the fluoroalkyl group. Such a wetting-property-modifiable layer can exhibit a large magnitude of change in the wetting property when energy is irradiated in a state in which the photocatalyst-containing layer is in contact therewith.
In the present invention, it is preferable that the organopolysiloxane is an organopolysiloxane obtained as a result of hydrolysis condensation or cohydrolysis condensation of at least one type or silicon compound generally represented by a formula YnSiX(4-n), wherein Y represents a group selected from the group consisting of the alkyl group, the fluoroalkyl group, the vinyl group, the amino group, the phenyl group and the epoxy group, X represents the alkoxyl group or the halogen group, and n represents an integer of 0 to 3. As a result of formation of the wetting-property-modifiable layer by using the above-mentioned organopolysiloxane as the material, a pattern-formed structure, in which a wetting-property pattern having a significantly different wetting characteristics from other portions has been formed, can be produced.
In the present invention, it is acceptable that the substrate for a pattern-formed structure is a self-supporting film, and at least one surface thereof is a film-like wetting-property-modifiable layer whose wetting property can be modified, such that a contact angle formed by a liquid on said wetting-property-modifiable layer is decreased upon irradiation of energy, by the action of the photocatalyst in the photocatalyst-containing layer. In such a pattern-formed structure, a pattern having different wetting characteristic can be obtained simply by effecting energy irradiation in a state in which one surface of a commercially available film, made of a predetermined material, is in contact with the photocatalyst-containing layer, which is advantageous in terms of cost reduction.
In the present invention, it is acceptable that the characteristic-modifiable layer is a decomposable and removable layer which is decomposed and removed by the action of the photocatalyst contained in the photocatalyst-containing layer. As a result of forming the characteristic-modifiable layer as a decomposable and removable layer which is decomposed and removed by the action of the photocatalyst contained in the photocatalyst-containing layer, the energy-irradiated portion thereof is decomposed and removed by the action of the photocatalyst. That is, the energy-irradiated portion can be completely decomposed and removed without necessity of any specific post-treatment. Therefore, for example, by designing the decomposable and removable layer as a photoresist and effecting exposure in a state in which the decomposable and removable layer is in contact with the photocatalyst-containing-layer side substrate, a pattern can be formed at the photo resist without necessity of carrying out the conventional development process. Other applications of various types are also possible in the structure of the present aspect.
In the present invention, it is preferable that a contact angle formed by a liquid on the decomposable and removable layer is different from a contact angle formed by the liquid on the substrate which has been exposed as a result of decomposition and removal of the decomposable and removable layer.
As a contact angle formed by a liquid on the decomposable and removable layer is different from a contact angle formed by the liquid on the substrate which has been exposed as a result of decomposition and removal of the decomposable and removable layer, as described above, at the energy-irradiated portion, the base material is exposed at the surface as a result of decomposition and removal of the decomposable and removable layer by the action of the photocatalyst. On the other hand, the decomposable and removable layer remains at the portion which is not been subjected to energy irradiation. Here, in a case in which a contact angle formed by a liquid on the decomposable and removable layer is different from a contact angle formed by the liquid on the exposed base material, if the decomposable and removable layer is made of a material having liquid repellency and the base material is made of a material having excellent affinity with a liquid (lyophilicity), for example, a portion of the decomposable and removable layer, at which portion a functional portion is to be formed, can be removed by irradiating energy in advance to the portion and thereby causing the photocatalyst to effect thereon. The energy-irradiated portion becomes a recessed portion which serves as an area having excellent lyophilicity, while the portion which is not subjected to energy irradiation becomes a projected portion which serves as a liquid-repellent area. Accordingly, the composition for the functional portion can be attached, easily and precisely, to the recessed portion in which the functional portion is to be provided and which serves as the area having excellent lyophilicity. Thus, in this case, the functional portion can be formed more precisely than the aforementioned case in which the characteristic-modifiable layer is a wetting-property-modifiable layer and there is no necessity of carrying out the post-treatment such as the developing or washing process after irradiation of energy. Therefore, the production process as a whole can be easily rendered a simpler state, whereby a functional element which is cheap and has a highly precise functional portion can be obtained.
In the present invention, it is preferable that the decomposable and removable layer is selected from the group consisting of a Self-Assembled Monolayer Film, a Langmuir-Blodgett""s Film and a Layer-by-Layer Self-Assembled Film. These materials are decomposed and removed by the action of the photocatalys contained in the photocatalyst-containing layer, so as to effect various functions.
In the present invention, it is acceptable that the irradiation of energy is carried out when the photocatalyst-containing layer is being heated. By heating the photocatalyst, the sensitivity of the photocatalys is enhanced, whereby modification of the characteristic at the characteristic-modifiable layer can be efficiently carried out.
The present invention discloses a photomask, comprising: a transparent base material; a light-shielding portion formed, in a pattern-like configuration, on the transparent base material; a primer layer formed on the transparent base material and the light-shielding portion; and a photocatalyst-containing layer formed on the primer layer. When such a photomask as described above is used, by simply irradiating energy by way of the photomask, patterns can be obtained as a result of modification of various characteristics, whereby a pattern-formed structure can be obtained efficiently.
Further, the present invention discloses a photomask, comprising: a transparent base material, a photocatalyst-containing layer formed on the transparent base material; and a light-shielding portion formed, in a pattern-like configuration, on the photocatalyst-containing layer, such that the shielding portion has thickness of 0.2 to 10 xcexcm.
The present invention also discloses a photomask, comprising: a transparent base material; a light-shielding portion formed, in a pattern-like configuration, on the transparent base material, such that the shielding portion has thickness of 0.2 to 10 xcexcm; and a photocatalyst-containing layer formed on the transparent base material and the light-shielding portion. In the aforementioned photomasks, by simply irradiating energy by way of the photomask onto the substrate for a pattern-formed structure having the aforementioned characteristic-modifiable layer, patterns are obtained as a result of modification of various characteristics, whereby a pattern-formed structure can be obtained efficiently.
The present invention discloses a functional element, comprising: a pattern-formed structure produced by the method of producing a pattern-formed structure according to the aforementioned method of producing a pattern-formed structure; and a functional portion provided at said pattern-formed structure. By using a pattern-formed structure of the present invention, a functional element can be easily obtained.
Examples of the functional element described in the aforementioned functional element, include a functional element made of metal. In this case, the functional element can be applied to a highly precise electric circuit board and the like.
The present invention discloses a color filter, in which the functional portion of the aforementioned functional element, is a pixel portion. Such a color filter includes highly minute pixel portions formed in a highly precise manner, and thus has an extremely high quality.
According to the present invention, patterns having various characteristics can be formed in a highly precise manner, without necessity to carry out any specific post-treatment after energy irradiation. Further, as the photocatalyst-containing-layer side substrate is removed from the pattern-formed structure after energy irradiation, the pattern-formed structure itself is free of the photocatalyst-containing layer. Accordingly, there is no concern that the pattern-formed structure deteriorates as time elapses due to the action of the photocatalyst. Yet further, as the gap between the photocatalyst-containing layer and the characteristic-modifiable layer is set within the above-mentioned range, there is achieved an excellent effect that a pattern-formed structure, having a pattern produced as a result of efficient and excellently precise modification of characteristic thereof, can be obtained.